• The Journal of the Convergence on Culture Technology
• /
• v.8 no.4
• /
• pp.253-261
• /
• 2022

The purpose of this study is to investigate the relationship between transformative leadership, team cohesion, and team performance of Chinese university taekwondo leaders. Specifically, it is to investigate the effect of transformative leadership on team cohesion and team performance and to verify the mediating effect of team cohesion in the relationship between transformative leadership and team performance. In order to achieve the research purpose, a total of 350 people were sampled after setting taekwondo leaders at Chinese universities as a population. The measurement tool used in this study was a questionnaire consisting of 5 items on demographic characteristics, a total of 19 questions on transformational leadership, 10 questions on team cohesion, and 4 questions on team performance. The validity of the questionnaire was verified through exploratory factor analysis, and the reliability was verified through reliability analysis. The reliability Cronbach's α of the questionnaire was found to be α=0.755-0.799 for transformative leadership, α=0.848, and α=0.740 for team performance. As the data processing method, exploratory factor analysis and reliability analysis, one-way analysis (one-way ANOVA), and multiple regression analysis were used using SPSS WIN. The conclusions derived through the above research methods and procedures are as follows. First, the transformative leadership of Taekwondo leaders at Chinese universities influenced team cohesion. Second, the transformative leadership of Taekwondo leaders at Chinese universities influenced team performance. Third, the team cohesiveness of Taekwondo leaders at Chinese universities influenced team performance. Fourth, the transformative leadership of Taekwondo leaders at Chinese universities not only directly affects team performance, but also indirectly affects team cohesion. Therefore, it is believed that Chinese Taekwondo players will help improve their performance by affecting team cohesion and team performance for the best games through the leader's variable leadership.

• Geophysics and Geophysical Exploration
• /
• v.26 no.1
• /
• pp.18-30
• /
• 2023

Submarine mud volcanos are topographic features that resemble volcanoes, and are formed due to eruptions of fluidized or gasified sediment material. They have gained attention as a source of subsurface heat, sediment, or hydrocarbons supplied to the surface. In the continental slope of the Canadian Beaufort Sea, mud volcano exists at various water depths. The MV420, is an active mud volcano erupting at a water depth of 420 meters, and it has been the subject of extensive study. The Korea Polar Research Institute(KOPRI) collected high-resolution seismic data and heat flow data around the caldera of the mud volcano. By analyzing the multi-channel seismic data, we confirmed the reverse-polarity reflector assumed by a gas hydrate-related bottom simulating reflector(BSR). To further elucidate the relationship between the BSR and gas hydrates, as well as the thermal structure of the mud volcano, a numerical geothermal model was developed based on the steady-state heat equation. Using this model, we estimated the base of the gas hydrate stability zone and found that the BSR depth estimated by multi-channel seismic data and the bottom of the gas hydrate stability zone were in good agreement., This suggests the presence of gas hydrates, and it was determined that the depth of the gas hydrate was likely up to 50 m, depending on the distance from the mud conduit. Thus, this depth estimate slightly differs from previous studies.

• Journal of The Korean Association For Science Education
• /
• v.43 no.1
• /
• pp.17-28
• /
• 2023

In line with the entry into the digital-based intelligent information society, the science curriculum emphasizes the cultivation of scientific competencies, and computer-based test (CBT) is drawing attention for assessment of competencies. CBT has advantages to develop items that have high fidelity, and to establish a feedback system by accumulating results into the database. However, it is necessary to solve the problems of improving validity of assessment results, lowering measurement efficiency, and increasing management factors. To examine students' responses to the introduction of the new assessment tools in the process of transitioning from paper-based test (PBT) to CBT, in this study, we analyzed the results of the PBT and the CBT conducted in 2021 National Assessment of Educational Achievement (NAEA). In particular, we sought to find the effects on student achievement when only the mode of assessment was changed without change of items, and the effect on student achievement when the items were composed including technology enhanced features that take advantage of CBT. This study is derived through the analysis of the results of 7,137 third-grade middle school students taking one among the three kinds of assessments, which were the PBT or two kinds of CBT. After the assessment, the percentage of correct answers and the item discriminations were collected for each group, and expert opinions on characteristics of response were collected through the expert council involving 8 science teachers with experience in NAEA. According to the results, there was no significant difference between students' achievement results in the PBT and the CBT-M, which means simple mode conversion type of CBT, so it could be explained that the mode effect did not appear. However, it was confirmed that the percentage of correct answers for the construct response items was somewhat high in the CBT, and this result was analyzed to be related to the convenience of the response. On the other hand, there were the items with a difference of more than 10%p from the correct answer rate of similar items, among the items to which technology enhanced functions were applied following the introduction of CBT. According to the analysis of response rate of options, these results could be explained that the students' level of understanding could be more closely grasped through the innovative items developed through the technology enhanced function. Based on the results, we discussed some guidance to be considered when introducing CBT and developing items through CBT, and presented implications.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.1
• /
• pp.1-17
• /
• 2023

Purpose. The purpose of this study was to examine the correlation between the finish line designs and the marginal adaptation of nonprecious metal alloy coping produced by different digital manufacturing methods. Materials and methods. Nonprecious metal alloy copings were made respectively from each master model with three different methods; SLS, milling and casting by computer aided design and computer aided manufacturing (CAD-CAM). Twelve copings were made by each method resulting in 72 copings in total. The measurement was conducted at 40 determined reference points along the circumferential margin with the confocal laser scanning microscope at magnification ×150. Results. Mean values of marginal gap of laser sintered copings were 11.8 ± 7.4 ㎛ for deep chamfer margin and 6.3 ± 3.5 ㎛ for rounded shoulder margin and the difference between them was statistically significant (P < .0001). Mean values of marginal gap of casted copings were 18.8 ± 20.2 ㎛ for deep chamfer margin and 33 ± 20.5 ㎛ for rounded shoulder margin and the difference between them was significant (P = .0004). Conclusion. Within the limitation of this study, the following conclusions were drawn. 1. The variation of finish line design influences the marginal adaptation of laser sintered metal coping and casted metal coping. 2. Laser sintered copings with rounded shoulder margin had better marginal fit than deep chamfer margin. 3. Casted copings with deep chamfer margin had better marginal fit than rounded shoulder margin. 4. According to the manufacturing method, SLS system showed the best marginal fit among three different methods. Casting and milling method followed that in order.

• Korean Journal of Culture and Social Issue
• /
• v.29 no.3
• /
• pp.361-404
• /
• 2023

This study utilized a cross-temporal meta-analysis to explore shifts in self-efficacy levels among Korean college students from 1999 to 2022. We expected that increases in authoritative parenting styles, narcissism levels among students, and individualism in Korea might have positively influenced the self-efficacy of college students over the years. Conversely, growing economic disparities, decreasing class mobility, and the increasing instability of job markets might have had negative effects on self-efficacy. To investigate this, we analyzed 293 self-efficacy studies involving Korean college students published between 1999 and 2022, encompassing a total of 88,904 participants. Our criteria included studies that used the three most prevalent self-efficacy scales in Korea, focused solely on Korean college students, were cross-sectional with a one-time self-efficacy measurement, and provided essential statistics for our analysis. The results indicated no significant change in the self-efficacy levels of Korean college students over the observed period from 1999 to 2022. Additionally, we examined correlations between self-efficacy and various social indicators from different time points (20, 15, 10, and 5 years prior, as well as the year of data collection). Findings revealed that both birth rate and consumer price fluctuation rate were consistently negatively correlated with self-efficacy, while gross national income was positively correlated. This study is the first to assess Korean college students' self-efficacy levels using a cross-temporal meta-analysis, offering foundational knowledge for implementing such analytical methods for subsequent research and providing an indirect assessment of the generational gap theory. Finally, the limitations of the study and the direction for future research were discussed.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.5
• /
• pp.417-426
• /
• 2023

Rapid climate change has resulted in glacial retreat and increased meltwater inputs in the Antarctic Peninsula, including King George Island where Marian Cove is located. Consequently, these phenomena are expected to induce changes in the water column light properties, which in turn will affect phytoplankton communities. To comprehend the effects of glacial retreat on the marine ecosystem in Marian Cove, we investigated on phytoplankton biomass (chlorophyll-a, chl-a) and various environment parameters in this area in December 2021 and January 2022. The average temperature at the euphotic depth in January 2022 (1.41 ± 0.13 ℃) was higher than that in December 2021 (0.87 ± 0.17 ℃). Contrastingly, the average salinity was lower in January 2022 (33.9 ± 0.10 psu) than in December 2021 (34.1 ± 0.12 psu). Major nutrients, including dissolved inorganic nitrogen, phosphate, and silicate, were sufficiently high, and thus, did not act as limiting factors for phytoplankton biomass. In December 2021 and January 2022, the mean chl-a concentrations were 1.03 ± 0.64 and 0.66 ± 0.15㎍ L^-1, respectively. The mean concentration of suspended particulate matter (SPM) was 24.9 ± 3.54 mgL^-1 during the study period, with elevated values observed in the vicinity of the inner glacier. However, relative lower chl-a concentrations were observed near the inner glacier, possibly due to high SPM load from the glacier, resulting in reduced light attenuation by SPM shading. Furthermore, the proportion of nanophytoplankton exceeded 70% in the inner cove, contributing to elevated mean fractions of nanophytoplankton in the glacier retreat marine ecosystem. Overall, our study indicated that freshwater and SPM inputs from glacial meltwater may possibly act as main factors controlling the dynamics of phytoplankton communities in glacier retreat areas. The findings may also serve as fundamental data for better understanding the carbon cycle in Marian Cove.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.31 no.1
• /
• pp.85-100
• /
• 2023

In this study, in order to improve the installation periodical inspection method of waste treatment facilities, we conducted on-site surveys of waste treatment facilities classified into six fields, grasped the problems of inspection methods, and made improvements accordingly. And revised the inspection method for waste treatment facilities. As a result, in the field of incineration and incineration heat recovery, inspection methods such as total temperature measurement and one-year TMS data comparison using a thermal imaging camera were established. And for the safety of the inspected person, it was applied so that the waste can be replaced with a document without opening it. In the case of landfill facilities, the details regarding the use of video information processing equipment and the management of facilities covering the upper part of the landfill facility are presented in the law, but the items that do not have a inspection methods were applied to the inspection method. In the case of Food Waste Treatment Facility, inspection methods were put in place to ensure compliance with standards for foul-smelling fish in odor control, a major cause of complaints. As a result, 10 out of 18 improvement proposals were reflected in the incineration and sterilization grinding, cement kiln, and incineration heat recovery facilities, and 11 out of 12 improvement proposals were reflected in the landfill facility. In the case of food distribution waste treatment facilities, 10 out of 12 improvement proposals were reflected, and a total of 31 inspection methods were improved.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.3
• /
• pp.21-29
• /
• 2023

In this study, the stress characteristics of temporary fixed steel rods were analyzed in the "temporary fixing system using internal prestressing tension", which is mainly applied to the construction of superstructures by FCM. It was difficult to confirm the changes in initial tensile force in this system because the steel rod was internally connected to the pier and the PSC BOX. Therefore, measurement was performed before and after the completion of each segment using an FBG sensor to measure the change in the micro length of the steel rod. The results of the analysis showed that 75% to 90% of the maximum vertical contraction of the steel rod that occurred until the completion of the cantilever segment occurred in the fixing ~ 1segment, and the maximum loss of initial prestressing force was 39%. Such excessive loss of tension force to 1 segment means that tension is needed to improve the precision of construction during the fixation, and re-tension is needed to secure stability for conduction of cantilever segments after the completion of 1segment. In the 2 ~ last segment, the stress of the steel rod decreased gradually, and in the summer, the decrease in stress tended to partially recover due to the increase in the length of the steel rod corresponding to the increase in the vertical volume of PSC BOX. The dominant factor in the stress change in 2~ last segment in this phenomenon is judged to be the change in the length of the steel rod according to the temperature. Unlike the change in length, the relaxation was 1.2-2.7%, which was mostly offset by the opposite stress corresponding to the temperature stress. Therefore, a plan was proposed to improve the internal stress, such as adjusting the fixation time.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.1
• /
• pp.18-25
• /
• 2022

Purpose: This study aimed to evaluate the color stability and antibacterial properties of the surface of polyethyl methacrylate (PEMA) resin with zirconia nanoparticles added. Materials and Methods: The control group was pure PEMA resin, and the experiment group was PEMA resin 15 mm in diameter and 2.5 mm in thickness disk-shaped specimens with 2, 4 and 8 w/v% of zirconia nanoparticles added, which were respectively divided into Group Z2, Group Z4, and Group Z8. After analyzing the surface roughness and color stability of the specimens, their antibacterial properties were evaluated using Porphyromonas gingivalis (P. gingivalis). The Statistical analysis was performed using when normality was met in the Shapiro-Wilk test, one-way ANOVA was used to test parameters, and Tukey's test was used as a post hoc test. When normality was not met, the Kruskal-Wallis test, a non-parametric test was used (P < 0.05). Results: The surface roughness measurement found that there was no significant difference between the experimental and control groups. The color stability evaluation showed that the Z2, Z4, and Z8 groups were within the color range of natural teeth. The adhesion of P. gingivalis was evaluated to be significantly reduced in Group Z2 compared to the control group (P < 0.05). In the Z2 group, Z4 group, and Z8 group, dead cells bacteria than the control group were observed. Conclusion: In conclusion, PEMA resin with zirconia nanoparticles added was within the range of natural teeth in color and reduced the adhesion of P. gingivalis.

• Journal of the Korean Society of Radiology
• /
• v.17 no.3
• /
• pp.315-325
• /
• 2023

The purpose of this study was to predict abdominal obesity with 3-Dimensional computed tomography (3D CT) measurements of kidneys by analyzing the correlation between kidney sizes and abdominal obesity level. The subjects were 178 healthy adults without underlying diseases who had a comprehensive health examination at the Health Medical Center of Jesus Hospital in Jeonju. Abdominal obesity was measured by CT cross-sectional image at the level of the umbilicus and divided into visceral fat area, subcutaneous fat area, visceral fat/total fat ratio. The average comparison of kidney sizes classified according to abdominal obesity were performed through one-way analysis of variance (ANOVA) and Scheffe test. Pearson correlation analysis was performed to correlate all measurement values. The results of kidney size ANOVA analysis according to abdominal obesity were as follows. The means of kidney measurements according to visceral fat classification were significantly different in all kidney measurements (p<0.05). And in case of subcutaneous fat classification, the means of kidney measurements by 3D CT of the severe obesity group were significantly different in the right kidney width (p<0.05). In case of visceral fat area/total fat area ratio, the means of kidney measurements by 3D CT of the severe obesity group were significantly different in both kidneys width (p<0.05). Pearson correlation between kidneys measurements and CT abdominal obesity showed that visceral fat area had the highest correlation with the left kidney width measured by 3D CT (r=0.467) and subcutaneous fat area had correlation with the right kidney width measured by 3D CT (r=0.249). The visceral fat area/total fat area ratio had correlation with the left kidney width measured by 3D CT (r=0.291).